WASHINGTON (AP) — Lynn Boyden, a college professor in Los Angeles who teaches website design, says she has developed two identities online: a public one for her professional life and a private one that only a few close friends can access. She tries to block advertising trackers when she can and limits what personal data might wind up on public sites.

It’s an approach that she says works, although it takes time and attention.

“It’s a sliding scale,” said Boyden of what information she chooses to share. “Some things are and should be private.”

Americans might be sharing more personal information online than ever through social networking sites and email. But they also want to better control who can see it, according to a study released Thursday by the Pew Research Center’s Internet and American Life Project.

The study reported that privacy concerns among Americans are on the rise, with 50 percent of Internet users saying they are worried about the information available about them online, up from 33 percent in 2009. Meanwhile, 86 percent of people surveyed have tried at least one technique to hide their activity online or avoid being tracked, such as clearing cookies or their browser history or using encryption.

While trying to avoid snooping — at least in some circumstances — is now commonplace, people cite varying reasons for doing so. About one-third said they had tried to conceal their activity from hackers or criminals, while 28 percent have tried to block advertisers. Others said they wanted to keep information private from family members or spouses, employers or the government.

“These findings reinforce the notion that privacy is not an all-or-nothing proposition for Internet users,” said Mary Madden, a senior researcher at Pew. “People choose different strategies for different activities, for different content, to mask themselves from different people, at different times in their lives. What they clearly want is the power to decide who knows what about them.”

Abby Drumm of Indianapolis and Dennis Wingo of Mountain View, Calif., are examples of people who want precise control over their information but for different reasons.

Drumm, a 20-year-old junior in college, said she isn’t worried about advertisers or government spies digging into her digital life. She’s mostly worried about offending family members. Drumm said she was confronted twice as a teenager about blog and Twitter posts that were perhaps “not family appropriate” but something she had assumed only close friends were reading.

Now, she says she has taken various steps to hide her online activity so fewer people can see what she posts or find her on various social networks.

Wingo, who owns an aerospace company, said his concern is the aggressive action being taken by the government, advertisers and hackers to invade consumers’ privacy online. He says that consumers shouldn’t have to opt out of advertising tracking and that businesses should pay him for anything they acquire about him online. He also says the government should have to encounter the same legal hurdles to read a person’s email as it does a private letter or document inside someone’s house, which isn’t the case because of outdated electronic privacy laws.

“Just because we’re on the Internet doesn’t mean we don’t have rights,” Wingo said. “That’s a part of public policy that has seriously lacked.”

The study found that 68 percent of people agreed that the law is insufficient to protect their privacy.

Boyden agreed that more could be done to protect consumer privacy. But because the Internet is largely an unregulated global enterprise, she thinks it’s probably more practical to start with educating people on basic steps they can take to protect themselves.

“There’s a lot of gray area in privacy,” she said. “And people’s comfort levels are different.”

The Pew study, done with help from Carnegie Mellon University, is based on data from 792 Internet and smartphone users contacted by telephone by Princeton Survey Research Associates International from July 11-14. The margin of error is 3.8 percentage points.